common mistake. 'neuken' = to ****
the '-er' suffix indicates an executer of the action, so it basically means 'person who x'
In this case, the verb 'neuken' is used, so the meaning of 'neuker' is logically: 'person who 'neuk's ('neuk' is 1st person singular, 'neukt' is 2nd and 3rd person singular') or, simplified: '******* (just like in English you see?). So 'moederneuker' is the literal translation of '*************

The entire text is a literal translation of 'Dutch ************, do you speak it?' Which is of course a parody on the famous quote from 'Pulp Fiction' by Quentin Tarantino